וְֽאֶת־הַקְּרָשִׁ֞ים תְּצַפֶּ֣ה זָהָ֗ב וְאֶת־טַבְּעֹֽתֵיהֶם֙ תַּעֲשֶׂ֣ה זָהָ֔ב בָּתִּ֖ים לַבְּרִיחִ֑ם וְצִפִּיתָ֥ אֶת־הַבְּרִיחִ֖ם זָהָֽב׃
And thou shalt overlay the boards with gold, and make their rings of gold for holders for the bars; and thou shalt overlay the bars with gold.
Read kabbalistic (mystical) interpretation of Exodus 26:29: and classical mystical sources.